Got the Beast last night. Yikes, the thing is big. It's going to take some getting used to. My left hand sits out pretty far to the left when playing. It's a little awkward. I think the stock RB guitars are actually a bit better, since they're only a little bit smaller than the WarBeast. The strum bar is a little too noisy for my taste. Also, the button for star power is right where I keep my palm when strumming, so I accidentally activated it once while playing last night.
The jury's still out on this one. It's definitely cool looking. I'll have to see if I can get used to it. If not, it's going back to Best Buy.